Modified amino acids for drug delivery

Abstract

The present invention relates to an oral delivery system, and in particular to modified amino acids or peptides for use as a delivery system of sensitive agents such as bioactive peptides. The modified amino acids or peptides can form non-covalent mixtures or microspheres with active biological agents. These mixtures or microspheres are suitable for oral administration of biologically active agents to animals. Methods for the preparation of such amino acids and peptides are also disclosed.

What is claimed is:  
     
       1. A compound having the formula                    
       wherein A is arginine, or citrulline. 
     
     
       2. A compound according to claim  1 , wherein A is acylated at two or more functional groups. 
     
     
       3. A compound according to claim  1 , wherein A is arginine. 
     
     
       4. A compound according to claim  2 , wherein A is arginine. 
     
     
       5. A compound according to claim  2 , wherein A is tryptophan. 
     
     
       6. A compound according to claim  1 , wherein A is citrulline. 
     
     
       7. A compound according to claim  2 , wherein A is citrulline. 
     
     
       8. A compound having the formula                    
       wherein A and B independently are arginine or leucine. 
     
     
       9. A compound according to claim  8 , wherein if A, B or A and B are arginine , A, B, or A and B are acylated at two or more functional groups. 
     
     
       10. A compound having the formula                    
       wherein A is arginine. 
     
     
       11. A compound according to claim  10 , wherein A is acylated at two or more functional groups. 
     
     
       12. A compound having the formula                    
       wherein A is leucine. 
     
     
       13. A compound having the formula                    
       wherein A is phenylglycine. 
     
     
       14. A compound having the formula                    
       wherein A is phenylglycine.